World map

# require packages: readxl,  tidyverse, ggplot2, raster, rgdal, viridis, sp
world.map = map_data("world")

head(world.map)
##        long      lat group order region subregion
## 1 -69.89912 12.45200     1     1  Aruba      <NA>
## 2 -69.89571 12.42300     1     2  Aruba      <NA>
## 3 -69.94219 12.43853     1     3  Aruba      <NA>
## 4 -70.00415 12.50049     1     4  Aruba      <NA>
## 5 -70.06612 12.54697     1     5  Aruba      <NA>
## 6 -70.05088 12.59707     1     6  Aruba      <NA>
p = ggplot(data=world.map, aes(x=long, y=lat, group=group, fill=factor(group))) 
p + geom_polygon(col="white") + theme(legend.position="none")

Get specific countries

countries = c("Vietnam", "Thailand", "Cambodia", "Malaysia", "Laos")
 
asean = map_data("world", region = countries)
 
ggplot(asean, aes(x=long, y=lat, group=group, fill=factor(group))) + geom_polygon(col="white") + theme(legend.position="none")